Method and apparatus for ventilating a patient with a breathing gas mixture formed from nitric oxide, air, and oxygen
First Claim
1. A method for administering inhaled nitric oxide to a subject breathing with the aid of a mechanical ventilator, a gas mixture for the subject being formed from supplies of oxygen, a balance gas, and a gas containing nitric oxide, said method comprising the steps of:
- (a) setting ventilation parameters, inspired oxygen concentration, and inspired nitric oxide concentration for the subject;
(b) determining from the settings of step (a) a total gas mixture flow rate (finsp) for the subject;
(c) determining a flow rate for the nitric oxide containing gas (FN2NO) based on the gas mixture flow rate (finsp);
(d) determining a flow rate for the balance gas (FAir) from the total gas mixture flow rate, the nitric oxide containing gas flow rate, and the inspired oxygen concentration established in step (a);
(e) determining the oxygen flow rate (FO2) as the difference between the total gas mixture flow rate (Finsp) and the inspiratory flow rate for the nitric oxide gas mixture (FN2NO) and balance gas (FAir); and
(f) providing the breathing gas mixture to the subject at a flow rate comprising the sum of the flow rate for the nitric oxide containing gas, the balance gas flow rate, and the oxygen flow rate.
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Accused Products
Abstract
A method and apparatus for supplying a breathing gas mixture to a patient in which a desired concentration of oxygen is maintained when nitric oxide (NO) is provided in the breathing gases. A clinician establishes at a ventilator, ventilation parameters for the patient, the inspired oxygen concentration, and the inspired NO dosage. From these quantities, a breathing gas mixture flow rate is determined. An instantaneous flow rate for an NO containing gas is determined, based on the concentration of nitric oxide in the supply gas and the instantaneous breathing gas mixture flow rate. An instantaneous flow rate for the supply of a balance gas, such as air, is determined using the breathing gas mixture flow rate, the instantaneous NO containing gas flow rate, and the inspired oxygen concentration established by the clinician. Finally, the instantaneous oxygen flow rate is determined as the difference between the inspiratory breathing gas flow rate and the instantaneous flow rates for the NO containing gas and the balance gas. A breathing gas mixture is thereafter provided to the patient at an instantaneous flow rate comprising the sum of the NO containing gas, balance gas, and oxygen flow rates. Actual gas flows are sensed by gas flow sensors and used to render the gas flow rates and the concentrations of NO and oxygen more accurate.
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Citations
26 Claims
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1. A method for administering inhaled nitric oxide to a subject breathing with the aid of a mechanical ventilator, a gas mixture for the subject being formed from supplies of oxygen, a balance gas, and a gas containing nitric oxide, said method comprising the steps of:
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(a) setting ventilation parameters, inspired oxygen concentration, and inspired nitric oxide concentration for the subject;
(b) determining from the settings of step (a) a total gas mixture flow rate (finsp) for the subject;
(c) determining a flow rate for the nitric oxide containing gas (FN2NO) based on the gas mixture flow rate (finsp);
(d) determining a flow rate for the balance gas (FAir) from the total gas mixture flow rate, the nitric oxide containing gas flow rate, and the inspired oxygen concentration established in step (a);
(e) determining the oxygen flow rate (FO2) as the difference between the total gas mixture flow rate (Finsp) and the inspiratory flow rate for the nitric oxide gas mixture (FN2NO) and balance gas (FAir); and
(f) providing the breathing gas mixture to the subject at a flow rate comprising the sum of the flow rate for the nitric oxide containing gas, the balance gas flow rate, and the oxygen flow rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. Apparatus for administering inhaled nitric oxide (NO) to a subject, a breathing gas mixture for the subject being formed from supplies of oxygen, a balance gas, and a gas containing NO, said apparatus comprising:
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a ventilator couplable to the supplies of oxygen and the balance gas and having control means for controlling the flow of air oxygen and the balance gas;
an NO delivery apparatus couplable to the supply of NO containing gas and having control means for controlling the flow of NO containing gas, the control means of said ventilator and the control means of said NO delivery apparatus being in data communication;
means for setting ventilation parameters, inspired oxygen concentration, and inspired NO concentration for the subject;
means for determining a total gas mixture flow rate (finsp) for the subject, a flow rate for the NO containing gas (FN2NO), a flow rate for the balance gas (FAir), and an oxygen flow rate (FO2); and
said determining means causing said control means of said ventilator and NO delivery apparatus to provide a breathing gas mixture to the subject at a flow rate comprising the sum of the flow rate for the NO containing gas, the balance gas flow rate, and the oxygen flow rate. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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Specification